1. Field of Invention
The present invention relates to a method of mounting an electronic component, a structure to mount an electronic component, an electronic component module, and an electronic apparatus.
2. Description of Related Art
An electronic component, such as an integrated circuit IC, can be used after being mounted on a circuit board. The related art includes various methods of mounting the electronic component on the circuit board. FIGS. 7(a) and 7(b) show a structure to mount an electronic component according to the related art. In FIG. 7(a), the electronic component 170, such as an IC, is mounted on the substrate 120 with an anisotropic conductive film (ACF) 190 sandwiched in between them. The anisotropic conductive film 190 disperses conductive particles 195 in a thermosetting resin 192. The conductive particles 195 are inserted between electrode pads 172 formed on an active surface of the electronic component 170 and electronic pads 122 formed on the surface of the substrate 120 to electrically connect the pads to each other. In addition, the electronic component 170 and the substrate 120 are mechanically connected to each other by the thermosetting resin 192 cured by heat treatment and the electrical connection between the electronic component 170 and the substrate 120 is protected.
As electronic components have become miniaturized, the clearances of the electrodes have become smaller. However, in the mounting method using the anisotropic conductive film, the clearances of the electrode pads have become so narrow that shorts are generated between the electronic pads, because the conductive particles 195 are disposed between horizontally adjacent electrode pads. In addition, since the clearances of the electronic pads have narrowed and the electrode pad itself is so small, the number of the conductive particles captured by each electrode pad has decreased, and the reliability of the electrical connection has deteriorated. Further, all of the expensive conductive particles cannot be used for the electrical connection.
Accordingly, International Publication WO 97/16848 pamphlet discloses a method of melting a base material composed of thermoplastic resin to adhere it to an active surface of the electronic component. FIG. 7(b) shows the mounted structure disclosed in International Publication WO 97/16848 pamphlet. In this mounted structure, a solder bump 274 is formed on an electronic component 270, such as an IC. In addition, a connection pattern 222 is formed on the bottom surface of the base material 220 composed of thermoplastic resin. Further, the electronic component 270 of the substrate 220 which has been heated at a temperature equal to or higher than the melting temperature is pressed onto the upper surface of the base material 220, the solder bump 274 passes through the base material 220 to contact the connection pattern 222. As a result, the electronic component 270 is electrically connected with the base material 220. In addition, the electronic component 270 is adhered and mechanically connected to the base material 220 solidified after melting it and the area around the solder bump 274 is protected.